1. Field of the Invention
The present invention relates to an auto-process camera, and more particularly, to a means for processing film units in an auto-process camera.
2. Description of the Prior Art
There is known a photographic process, which is frequently referred to as auto-process, and according to which, a film is provided in the form of individual units including a layer of photosensitive image-recording material supported on one of a pair of sheets and also including at least one breakable pod containing a processing solution, more particularly, for example, one type of the film unit comprises at least a negative image layer exposable to produce a negative or latent image of an object and a positive image layer on which a positive, viewable image corresponding to the image produced on the negative image layer may be formed under the influence of a developing and processing solution which is diffused through the film unit, it being also possible for film units to contain other layers, depending on film unit type and purpose. It is usual practice to provide processing solution in breakable pods which are embedded in the film unit structure near one end portion thereof, and to provide, in an associated camera, pressure means, which is suitably constituted by a pair of rolls, for breaking open the pods. After being loaded into a camera and exposed, a film unit is moved, with the film unit end containing the processing solution pods foremost, and brought into engagement with and drawn through the pressure rolls, which break and open the pods and cause extrusion of the processing solution and diffusion thereof through the film unit, the film unit being brought immediately afterwards to the exterior of the camera, there thus being made available a viewable print a very short time after exposure of the film unit, without making it necessary for a photographer to proceed to a separate, specially equipped location for development and processing of film. The film unit may be drawn through the processing rolls either by means of a leader, which is constituted by a strip of paper or similar material, and is attached at one end to the film unit and may be pulled manually, or by means of actuation of one or both the processing rolls by mechanical or electrical drive means provided in the associated camera. In the latter case, means are provided in the camera to forward the exposed film unit from an exposure station to, and into engagement with the processing rolls, and the processing rolls also act to forward the film unit out of the camera, which offers the advantage, for the photographer, of ease of manipulation. In either case, it is essential that the pressure exerted by the processing rolls be sufficient to ensure efficient spreading of processing solution through the film unit, but at the same time the processing solution must be distributed therethrough uniformly. The thickness of the distributed processing solution over the entire length and width of the film unit not only directly influences the quality of a photographic print of the subject image, but also is an important factor for the determination of the amount of processing solution contained in the pods provided in the film unit in the manufacturing thereof. For example, in the diffusion transfer photography, the quality of the photographic print of the subject image is directly related to the thickness distribution of the processing solution between the negative image layer and the positive image layer and variations in average thickness of the same therebetween decisively affect the balance of the color and the contrast of the image of the final photographic print.
Furthermore, in cases where opaque liquids are employed as the processing solution for shielding the negative image layer from light, such irregular distribution of the processing solution through the film unit may transmit light irrelevant to the exposure of the subject image, thus giving rise to blur or uneven shade of color in the final print.
Conventionally, the film unit processing means of the above described type, for example, one incorporated in the so-called "auto-process" camera based on the diffusion transfer photography includes a pair of rolls disposed in parallel relation to each other, with a predetermined space kept therebetween, or a roll having a corresponding rigid member spaced a predetermined distance from the former, or a pair of rigid members disposed in parallel to each other so as to squeeze the pod therebetween and to cause the pod provided in the leading edge of the film unit to rupture for spreading the solution contained therein in the form of a layer within the film unit as the same unit passes therethrough.
The conventional arrangement as described above in which pressing members such as rolls or rigid members are disposed in pairs in parallel to each other with a predetermined distance therebetween, however, has such a disadvantage that uniform thickness distribution troughout the film unit is difficult to achieve due to slight elastic deformation of the pressure members, construction of the film unit and viscosity of the developing solution or the like. In order to overcome such a disadvantage, there is conventionally proposed a processing means as shown in FIG. 1, wherein a crown roll 1 having a diameter gradually increasing toward the central portion thereof is provided in parallel with an ordinary roll 2 having the same diameter over the entire length thereof, which the crown roll, however, requires an extremely high accuracy in the axial diameter variation thereof, resulting in difficulties and consequent high cost in manufacturing.
Accordingly, an essential object of the present invention is to provide a film processing means for use in an auto-process camera in which thickness distribution and average thickness of the processing solution to be spread within a film unit can be controlled as desired with substantial elimination of disadvantages inherent in the conventional processing means.
Another important object of the present invention is to provide a film processing means of the above described type which is accurate and stable in functioning .
A further object of the present invention is to provide a film processing means of the above described type which is simple in construction and can be manufactured at low cost for incorporation into an auto-process camera.